Cellular gypsum product



Reissued Mar. 19, 1935 CELLULAR GYPSUM PRODUCT Gustave Adolph New, Lakewood, Ohio, assignor,

by mesne assignments, to Buffalo-Electro- Chemical Co., Inc., Buffalo, N. Y.

No Drawing. Original No. 1,770,797, dated Jill v 15,1930, Serial No. 242,960, December 27, 1927. Application for-reissue August 21, 1933, Serial v 8 Claims. (01. 1os 24) This invention relates to improvements in cellular gypsum products, and more particularly to a composition of matter for building purposes of which calcined gypsum is the base, andhaving a 5 cellular texture calculated to promote lightness in weight and to improve the heat and sound insulating properties of the material when formed into boards or blocks, cast as an insulating filler or applied to wall surfaces as a covering having acoustic properties.

The object of the invention is to provide an improved composition for a cellular gypsum having the requisite qualities of lightness, hardness and uniformityof cellular texture by the utilization and addition to the basic calcined gypsum of relatively inexpensive ingredients, having the property of creating a uniform and stable cell structure within a comparatively short period of time.

The meritof a composition having the foregoing characteristics will be better appreciated from a brief discussion of what has been accomplished heretofore in the attempt to produce a satisfactory cellular mix. In general, the basis of cell production has been the generation or liberation of gases within the mass by the addition of certain chemical ingredients reacting in the presence of water, giving off a free gas calculated to spread throughout the mass and form a cellular texture whenthe same has set and hardened. The more common gas producing ingredients used have been an acid salt, such as aluminum sulphate, and a carbonate of the alkali group,-so dium, magnesium or the like-the resulting gas being carbon dioxide (CO2) As a chemical phenomenon, the generation of CO2 by this reaction has long been known and used in other arts, as for instance, in the baking of bread, and hence the introduction of this gas into a mass of calcined gypsum presents no particular problem. However, the control of the gas after it has been liberated has beenthe source of considerable difficulty, and it is to the solution of this problem that considerable effort has been directed. It follows naturally'that a gas liberated into a more or less plastic mass will seek to rise and escape, and therefore means must be employed for holding or entangling the gas bubbles within the mass. This result has been accomplished to some degree by adding so-called entangling agents, such as glue, gelatinous substances and one of the several commercial retarders, so-called. But these expedients have only proved to be partially effective, since once having entrapped the gas, it is essential that it shall be distributed in bubbles or cells of uniform size and uniformly throughout the mass, since otherwise the cells would tend-to be larger at, the top than atthe bottom with the result that the structure would be'relatively weak and spongy'at the top'and quite dense at thebot- 'Another difficulty encountered has been the prolongation ,of the period required "to complete the gas' generation, with the resultthat the cells continue to form'and the bulk of the'material to increase for a considerable time after it has been poured andcommenced to set." Hence it is diflicult, if not impossible, to gauge the volume of the wet mixture that'will. occupy any given space, or the ultimate thickness of a layerof the material to be spread over: a given area. In short, the real problem is to control the mix, and hence to .produce a mixture which can be accurately controlled as to the uniformity of cell structure, and the stability of the mass when in its plastic or wet condition.

In previous applications filed by me, to wit: Serial No. 192,793, filedMay 19', 1927;No. 197,517, filed June 8, 1927; No. 213,227, filed August 15', 1927; and No. 237,985, filed December 5,1927, I have sought to overcome the technical difliculties hereinabove discussed and have disclosed as many different and practical methods of attaining this end, by the use of different ingredients and combinations of ingredients. The present disclosure is still a further improvement and development in the same direction and one in which I have sought to bring the factors of uniformity and stability of cell structure within still narrower limits of' probable error, and at the same time'to simplify the process of productionand to improve the quality of the product in other respects. The extent to which this object has been attained will be seen from'the following discussion:

As heretofore, the basic ingredient'of the com position is commercial calcined gypsum, that'is, raw gypsum rock partially calcined at 'a-temperature of about 350 (CaSO-;.1/2Hz0 To'a given volume or weight of the gypsum is added relatively small amounts of hydrogen peroxide (H202) a catalyzer such as blood flour, together with an accelerator such as anhydrate,"a waste product in the manufacture of g'ypsurnproducts or the waste gypsum products themselves, as for instance, finely ground plaster board, block or other previously manufactured product which available as waste.

The hydrogen peroxide is the principal ing're client added to generate the gas upon which the cellular structure is dependent, its chemical properties being best known by the readiness with gypsum and blood flour in the proportions of substantially two hundred (200) parts to one (1) part, and mixing the same with water containing substantially one (1) part of a three per cent (3%) solution of hydrogen peroxide.

2. A method of producing a cellular gypsum mix, consisting of adding to a predetermined quantity of calcined gypsum, a relatively small quantity of blood flour, adding to a predetermined quantity of water a relatively small amount of hydrogen peroxide solution, and mixing the solid and liquid materials together into a plastic mass.

3. A method of producing a cellular gypsum product consisting of adding a relatively small quantity of blood flour to a predetermined quantity of calcined gypsum and mixing therewith a quantity of a solution of hydrogen peroxide and water sufiicient to form a plastic mass.

4. A method of producing a cellular product consisting of mixing a solution of hydrogen peroxide and water with a mixture of calcined gypsum and blood flour.

5. A method of producing a cellular gypsum product consisting of mixing a solution of hydrogen peroxide and water with a mixture of calcined gypsum, blood flour and an accelerator.

6. A method of producing a cellular gypsum mix consisting of forming a dry mix of calcined gypsum and blood flour and mixing the same with water containing less than one per cent (1%) 01' hydrogen peroxide.

7. A method of producing a cellular gypsum mix consisting of forming a dry mix of calcined gypsum, blood flour and an accelerator and mixing the same with water containing less than one per cent (1%) of hydrogen peroxide.

8. A method of producing a cellular gypsum mix consisting of forming a dry mix of calcined gypsum and relatively small amounts of blood flour and an accelerator and mixing the same with water containing a relatively small quantity of hydrogen peroxide.

GUSTAVE ADOLPH NEW. 

